jem::util::Enumerator Class Reference

Iterates over a set of objects. More...

Inheritance diagram for jem::util::Enumerator:

Public Member Functions
virtual Class *	getClass () const
	Returns the Class instance representing the runtime class of this object. More...
virtual bool	atEnd () const =0
	Checks whether this enumerator points to an end object. More...
virtual void	toNext ()=0
	Advances this enumerator to the next object. More...
virtual Ref< Object >	get () const =0
	Returns the current object. More...
Public Member Functions inherited from jem::Object
virtual String	toString () const
	Returns a short textual description of this object. More...
virtual long	hashValue () const
	Returns a hash value for this object. More...
virtual bool	equals (const Ref< Object > &obj) const
	Tests whether two objects are equal. More...
Ref< Object >	clone () const
	Returns a copy of this object. More...

Static Public Member Functions
static Class *	makeClass ()
static Class *	getType ()
Static Public Member Functions inherited from jem::Object
static Class *	getType ()
	Returns the Class instance representing the Object class. More...

Protected Member Functions
virtual	~Enumerator ()
Protected Member Functions inherited from jem::Collectable
	Collectable ()
	Creates an empty Collectable. More...
	~Collectable ()
	Frees resources. More...

Detailed Description

#include <jem/util/Enumerator.h>

The abstract class Enumerator can be used to iterate over a collection of objects. An Enumerator can be viewed as a type of forward iterator with virtual member functions.

An Enumerator either points to an object in a collection, or to a special end object that is located one position past the last object in the collection. The member function atEnd() can be used to check whether an enumerator points to a regular object or to an end object. Note that end objects can not be accessed; they are conceptual objects that are not physically stored in memory.

The following code fragment demonstrates how the Enumerator class is typically used.

void print ( io::Writer& out, Enumerable& collection )
{
  Ref<Enumerator> e = collection.getEnumerator ();

  for ( ; ! e->atEnd(); e->toNext() )
  {
    out << e->get()->toString();
  }
}

See also

Enumerable

Constructor & Destructor Documentation

virtual jem::util::Enumerator::~Enumerator ( )

protectedvirtual

Member Function Documentation

static Class* jem::util::Enumerator::makeClass ( )

static

static Class* jem::util::Enumerator::getType ( )

static

virtual Class* jem::util::Enumerator::getClass ( ) const

virtual

Returns a pointer to the Class instance representing the runtime class of this object. If T denotes the runtime class of this object, then this function is equivalent with T::getType(). The pointer is valid during the entire lifetime of the program.

Returns

A pointer to the Class instance representing the runtime class of this object.

Reimplemented from jem::Object.

Reimplemented in jem::util::DictionaryEnumerator.

virtual bool jem::util::Enumerator::atEnd ( ) const

pure virtual

Checks whether this enumerator points to an end object that marks the end of an object collection.

Returns

true if this enumerator points to an end object, or false otherwise.

virtual void jem::util::Enumerator::toNext ( )

pure virtual

Advances this enumerator to the next object in the collection, or to the end object if there is no next object. This function may not be called if this enumerator already points to the end object.

Precondition

this->atEnd() == false

Implemented in jem::util::SequenceEnumerator.

virtual Ref<Object> jem::util::Enumerator::get ( ) const

pure virtual

Returns a reference to the object that this enumerator is currently pointing to. This function may not be called if this enumerator is pointing to an end object.

Precondition

this->atEnd() == false

Returns

A reference to the current object.

Implemented in jem::util::DictionaryEnumerator, and jem::util::MapEnumerator.